Dual spin valve sensor with AP pinned layers

1. A magnetic read head which has an air bearing (ABS) surface comprising: nonmagnetic electrically nonconductive first and second read gap layers; a spin valve sensor being located between the first and second read gap layers; ferromagnetic first and second shield layers; and the first and second read gap layers being located between the first and second shield layers; the spin valve sensor including: a ferromagnetic free layer structure; first and second antiparallel (AP) pinned layer structures; the first AP pinned layer structure having a first antiparallel (AP) coupling layer located between ferromagnetic first and second antiparallel (AP) pinned layers and the second AP pinned layer structure having a second antiparallel (AP) coupling layer located between ferromagnetic third and fourth antiparallel (AP) pinned layers; the second and third AP pinned layers having magnetic moments that are perpendicular to the ABS and parallel with respect to one another; a nonmagnetic electrically conductive first spacer layer located between the free layer structure and the second AP pinned layer and interfacing the second AP pinned layer; a nonmagnetic electrically conductive second spacer layer located between the free layer structure and the third AP pinned layer and interfacing the third AP pinned layer; the first and third AP pinned layers having magnetic thicknesses that are greater or less than magnetic thicknesses of the second and fourth AP pinned layers respectively; each of the second and third AP pinned layers exerting a ferromagnetic coupling field on the free layer structure; and the first and second AP pinned layer structures having a net demagnetizing field that counterbalances the ferromagnetic coupling fields on the free layer structure.

2. A magnetic head assembly having an air bearing surface (ABS), comprising: a write head including: ferromagnetic first and second pole piece layers that have a yoke portion located between a pole tip portion and a back gap portion; a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers; an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and the first and second pole piece layers being connected at their back gap portions; and a read head including: a spin valve sensor; nonmagnetic electrically nonconductive first and second read gap layers; the spin valve sensor being located between the first and second read gap layers; a ferromagnetic first shield layer; and the first and second gap layers being located between the first shield layer and the first pole piece layer; and the spin valve sensor including: a ferromagnetic free layer structure; first and second antiparallel (AP) pinned layer structures; the first AP pinned layer structure having a first antiparallel (AP) coupling layer located between ferromagnetic first and second antiparallel (AP) pinned layers and the second AP pinned layer structure having a second antiparallel (AP) coupling layer located between ferromagnetic third and fourth antiparallel (AP) pinned layers; the second and third AP pinned layers having magnetic moments that are perpendicular to the ABS and parallel with respect to one another; a nonmagnetic electrically conductive first spacer layer located between the free layer structure and the second AP pinned layer and interfacing the second AP pinned layer; a nonmagnetic electrically conductive second spacer layer located between the free layer structure and the third AP pinned layer and interfacing the third AP pinned layer; and the first and third AP pinned layers having magnetic thicknesses that are greater or less than magnetic thicknesses of the second and fourth AP pinned layers respectively; each of the second and third AP pinned layers exerting a ferromagnetic coupling field on the free layer structure; and the first and second AP pinned layer structures having a net demagnetizing field that counterbalances the ferromagnetic coupling fields on the free layer structure.

3. A magnetic disk drive including at least one magnetic head assembly that has an air bearing surface (ABS) and that includes a write head and a read head, comprising: a write head including: ferromagnetic first and second pole piece layers that have a yoke portion located between a pole tip portion and a back gap portion; a nonmagnetic write gap layer located between the pole tip portions of the first and second pole piece layers; an insulation stack with at least one coil layer embedded therein located between the yoke portions of the first and second pole piece layers; and the first and second pole piece layers being connected at their back gap portions; and a read head including: a spin valve sensor; nonmagnetic electrically nonconductive first and second read gap layers; the spin valve sensor being located between the first and second read gap layers; a ferromagnetic first shield layer; and the first and second read gap layers being located between the first shield layer and the first pole piece layer; and the spin valve sensor including: a ferromagnetic free layer structure; first and second antiparallel (AP) pinned layer structures; the first AP pinned layer structure having a first antiparallel (AP) coupling layer located between ferromagnetic first and second antiparallel (AP) pinned layers and the second AP pinned layer structure having a second antiparallel (AP) coupling layer located between ferromagnetic third and fourth antiparallel (AP) pinned layers; the second and third AP pinned layers having magnetic moments that are perpendicular to the ABS and parallel with respect to one another; a nonmagnetic electrically conductive first spacer layer located between the free layer structure and the second AP pinned layer and interfacing the second AP pinned layer; a nonmagnetic electrically conductive second spacer layer located between the free layer structure and the third AP pinned layer and interfacing the third AP pinned layer; and the first and third AP pinned layers having magnetic thicknesses that are greater or less than magnetic thicknesses of the second and fourth AP pinned layers respectively; each of the second and third AP pinned layers exerting a ferromagnetic coupling field on the free layer structure; and the first and second AP pinned layer structures having a net demagnetizing field that counterbalances the ferromagnetic coupling fields on the free layer structure; a housing; a magnetic disk rotatably supported in the housing; a support mounted in the housing for supporting the magnetic head assembly with said ABS facing the magnetic disk so that the magnetic head assembly is in a transducing relationship with the magnetic disk; a spindle motor for rotating the magnetic disk; an actuator positioning means connected to the support for moving the magnetic head assembly to multiple positions with respect to said magnetic disk; and a processor connected to the magnetic head assembly, to the spindle motor and to the actuator for exchanging signals with the magnetic head assembly, for controlling movement of the magnetic disk and for controlling the position of the magnetic head assembly.

4. A method of making a magnetic read head which has an air bearing surface (ABS), comprising the steps of: forming nonmagnetic electrically nonconductive first and second read gap layers; forming a spin valve sensor between the first and second read gap layers; forming ferromagnetic first and second shield layers; and forming the first and second read gap layers between the first and second shield layers; making the spin valve sensor comprising the steps of: forming a ferromagnetic free layer structure; forming first and second antiparallel (AP) pinned layer structures wherein the first AP pinned layer structure has a first antiparallel (AP) coupling layer located between ferromagnetic first and second antiparallel (AP) pinned layers and the second AP pinned layer structure has a second antiparallel (AP) coupling layer located between ferromagnetic third and fourth antiparallel (AP) pinned layers; forming the second and third AP pinned layers with magnetic moments that are perpendicular to the ABS and parallel with respect to one another; forming a nonmagnetic electrically conductive first spacer layer between the free layer structure and the second AP pinned layer and interfacing the second AP pinned layer; forming a nonmagnetic electrically conductive second spacer layer between the free layer structure and the third AP pinned layer and interfacing the third AP pinned layer; and forming the first and third AP pinned layers with magnetic thicknesses that are greater or less than magnetic thicknesses of the second and fourth AP pinned layers respectively; the forming of the second and third AP pinned layers causing each of the second and third AP pinned layers to exert a ferromagnetic coupling field on the free layer structure; and forming the first and second AP pinned layer structures with a net demagnetizing field that counterbalances the ferromagnetic coupling fields on the free layer structure.

5. A method of making magnetic head assembly that has an air bearing surface (ABS), comprising the steps of: making a write head including the steps of: forming ferromagnetic first and second pole piece layers in pole tip, yoke and back gap regions wherein the yoke region is located between the pole tip and back gap regions; forming a nonmagnetic electrically nonconductive write gap layer between the first and second pole piece layers in the pole tip region; forming an insulation stack with at least one coil layer embedded therein between the first and second pole piece layers in the yoke region; and connecting the first and pole piece layers at said back gap region; and making a read head including the steps of: forming nonmagnetic electrically nonconductive first and second read gap layers; forming a spin valve sensor between the first and second read gap layers; forming the first and second read gap layers between the first shield layer and the first pole piece layer; and a making of the spin valve sensor comprising the steps of: forming a ferromagnetic free layer structure; forming first and second antiparallel (AP) pinned layer structures wherein the first AP pinned layer structure has a first antiparallel (AP) coupling layer located between ferromagnetic first and second antiparallel (AP) pinned layers and the second AP pinned layer structure has a second antiparallel (AP) coupling layer located between ferromagnetic third and fourth antiparallel (AP) pinned layers; forming the second and third AP pinned layers with magnetic moments that are perpendicular to the ABS and parallel with respect to one another; forming a nonmagnetic electrically conductive first spacer layer between the free layer structure and the second AP pinned layer and interfacing the second AP pinned layer; forming a nonmagnetic electrically conductive second spacer layer between the free layer structure and the third AP pinned layer and interfacing the third AP pinned layer; and forming the first and third AP pinned layers with magnetic thicknesses that are greater or less than magnetic thicknesses of the second and fourth AP pinned layers respectively; the forming of the second and third AP pinned layers causing each of the second and third AP pinned layers to exert a ferromagnetic coupling field on the free layer structure; and forming the first and second AP pinned layer structures with a net demagnetizing field that counterbalances the ferromagnetic coupling fields on the free layer structure.